LogDog: Add collector service implementation.

common/gcloud/gcps/ackbuffer/ack.go

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package ackbuffer
+
+import (
+        "github.com/luci/luci-go/common/gcloud/gcps"
+        "golang.org/x/net/context"
+)
+
+// Acknowledger sends ACKs to a Pub/Sub interface.
+//
+// gcps.PubSub naturally implements this interface.
+type Acknowledger interface {

[dnj (Google), 2016/01/21 04:36:24]

These changes allow better interoperability between standard interface and the
ackbuffer.

+        // Ack acknowledges one or more Pub/Sub message ACK IDs.
+        Ack(ctx context.Context, ackIDs ...string) error
+
+        // AckBatchSize returns the maximum number of ACKs that can be sent at a time.
+        AckBatchSize() int
+}
+
+type gcpsACK struct {
+        ps    gcps.PubSub
+        sub   gcps.Subscription
+        batch int
+}
+
+// NewACK creates a Acknowledger instance from a gcps.PubSub implementation.
+//
+// If batch is <= 0, the maximum ACK batch size will be used.
+func NewACK(ps gcps.PubSub, s gcps.Subscription, batch int) Acknowledger {
+        if batch <= 0 {
+                batch = gcps.MaxMessageAckPerRequest
+        }
+
+        return &gcpsACK{
+                ps:    ps,
+                sub:   s,
+                batch: batch,
+        }
+}
+
+func (a *gcpsACK) Ack(c context.Context, ackIDs ...string) error {
+        return a.ps.Ack(c, a.sub, ackIDs...)
+}
+
+func (a *gcpsACK) AckBatchSize() int {
+        return a.batch
+}